Formatting CIColorCube data

Question

Recently, I\'ve been trying to set up a CIColorCube on a CIImage to create a custom effect. Here\'s what I have now:

uint8_t color_cube_data[8*4] = {
    0,          


        

Answer 1

Your problem is that you are using value 1(which is next to zero) for alpha channel, max for uint8_t is 255

See example below:

CIFilter *cubeHeatmapLookupFilter = [CIFilter filterWithName:@"CIColorCube"];

int dimension = 4;  // Must be power of 2, max of 128
int cubeDataSize = 4 * dimension * dimension * dimension;

unsigned char cubeDataBytes[cubeDataSize];

//cubeDataBytes[cubeDataSize]
unsigned char cubeDataBytes[4*4*4*4] = {
    0,      0,      0,      0,
    255,    0,      0,      170,
    255,    250,    0,      200,
    255,    255,    255,    255
};

NSData *cube_data = [NSData dataWithBytes:cubeDataBytes length:(cubeDataSize*sizeof(char))];

//applying
[cubeHeatmapLookupFilter setValue:myImage forKey:@"inputImage"];
[cubeHeatmapLookupFilter setValue:cube_data forKey:@"inputCubeData"];
[cubeHeatmapLookupFilter setValue:@(dimension) forKey:@"inputCubeDimension"];

This is link to full project https://github.com/knerush/heatMap